The invention relates to an iterative interpolation technique for determining at least one interpolated video information value in an image that exhibits a number of image regions arrayed in matrix fashion having at least one image region to be interpolated.
Interpolation techniques for determining a video information value for an image region are required in image processing for a variety of intended applications.
One intended application is the generation of frames from fields transmitted in television technology. Here, between every two lines of an existing field, an intermediate line having a number of pixels is interpolated in order to obtain a frame. An interpolation method for generating such intermediate lines is described for example in DE 102 32 372 A1 (Hahn et al.).
A further intended application for an interpolation method is the enhancement of image resolution. Here, between existing lines and columns of an image, further lines and columns are generated by interpolation in order to enhance the image resolution. A method for this purpose is described for example in U.S. Pat. No. 6,229,570 B1 (Bugwadia et al.).
Interpolation methods are further needed in video transmission methods in which an image to be transmitted is divided into image blocks and transmitted blockwise. If a block is not transmitted or is transmitted with errors because of a transmission error, its video content is to be interpolated at the receiver end. A method for this purpose is described for example in Meisinger and Kaup, “Frequency-Selective Extrapolation for Spatial Error Masking of Video Data Received with Interference,” “Electronic Media,” 10th Dortmund Television Seminar, ITG Technical Report 179, September 2003, pages 189-194.
A further intended application for interpolation methods in image processing is to enhance the resolution of a motion-vector field. It is sufficiently well known in image processing to divide into individual image blocks an image that is part of an image sequence having a plurality of successive images and to associate a motion vector with each of these image blocks using a motion estimation technique. These vectors jointly form a motion-vector field. Such a motion vector associated with a block contains an item of information as to the position in a preceding and/or succeeding image of the image sequence in which the content of this block is again found. This item of information can be used for directionally correct generation of intermediate images between two images of an image sequence. In motion estimation it is desirable to obtain the smallest possible blocks with each of which a motion vector is associated. This, however, increases the effort in motion estimation.
In order to hold this effort for motion estimation within limits, it is known to enhance the resolution of the vector field after motion estimation by dividing the initially existing image blocks into smaller blocks with which motion vectors are associated by the use of an interpolation technique in a fashion taking account of the motion vectors of the larger original blocks. A method for this purpose is described for example in U.S. Pat. No. 5,148,269 (de Haan et al.).
A further intended purpose for interpolation methods is to generate intermediate images that are disposed temporally between existing images of an image sequence.
There is a need for an improved interpolation technique for determining at least one interpolated video information value in an image that exhibits a number of image regions arrayed in matrix fashion, of which at least one image region is to be interpolated, and that is disposed temporally between at least two images.